Gas discharge apparatus



2 Sheets-Sheet 1 Filed Dec. 11, 1958 FIG].

Oct. 1, 1963 Filed Dec. 11, 1958 P. C. THONEMANN GAS DISCHARGE APPARATUS 2 Sheets-Sheet 2 3,105,806 Patented Oct. 1, 1963 United'states Patent ice 3,105,806 GAS DISCHARGE APPARATUS Peter Clive Thonemann, Oxford, England, assiguor to United Kingdom Atomic Energy Authority, London,

England Filed Dec. 11, 1958, Ser. No. 779,607 Claims priority, application Great Britain Oct. 15, 1957 3 Claims. (Cl. 204-1933) increase its effective length.

The present application is 'a continuation-in-part of copending application Serial No. 766,935, filed October 13, 1958, and now abandoned.

In apparatus of the kind set forth, short-wave spatial instabilities of the discharge channel can becontrolled by the application of an axial magnetic stabilising field which is trapped within the discharge channel as the latter constricts in cross-section after initiation. With the aforementioned type of liner, however, any applied axial field existing outside the liner, e.g. between liner and torus, continues to leak rapidly into the liner after the field within the liner has been trapped by the discharge. This leakage of axial field into the space between liner and discharge tends to upset the spatial stability of the discharge channel and it is an object of the present invention to reduce the leakage rate of the axial field into the liner.

According to the present invention in apparatus of the kind set forth, the high-resistance liner is provided with circumferential conducting means around its small circumference adapted when energised to produce a magnetic field which opposes the entry \of an applied axial magnetic field into the liner.

The conducting means may comprise a plurality of closed conductors adapted to increase the conductivity of the liner around its small circumference, whereby the axial field in trying to enter the liner induces currents in the closed conductors which produce an opposing field.

The liner may be of the corrugated type, said conductors being arranged to lie within the corrugations. Said conducting meansmay be external to the liner.

To enable the nature of the present invention to be more readily understood attention is directed by way of example to the accompanying drawings wherein:

FIG. 1 is an enlarged view of the section of the apparatus shown in FIG. 3 between the lines AA and BB therein.

FIG. 2 is an elevation of one of the conductors to a' different scale.

FIG. 3 is a diagrammatic cross-sectional plan view of the gas discharge apparatus described in the aforemen tioned specification modified in accordance with the presapplied via windings (not shown) on the outside of the torus initially fills all the space within the torusand liner. When a pulsed ring discharge is initiated in the gas in the liner, the magnetic field within the liner is trapped in the discharge channel, but the magnetic field existing in the space 3 between liner and torus is unaffected and leaks thereafter into the liner.

To reduce the leakage rate there is fitted in each corrugation, outside the liner, a circumferential closed conductor 4. In trying to enter the liner, the magnetic field induces currents in these conductors which produce an opposing field.

In the aforementioned embodiment, the corrugated liner was of 18/8 stainless steel approximately 20 thou. thick, with a corrugation depth of inch and 2 /2 corrugations per inch. The conductors 4 fitted in accordance with the present invention are of copper and are swaged from inch copper rod to a roughly oval crosssection' of about 0.070 in; x 0.170 in. as shown in FIG. 1, so that they can be fitted at the bottom of each corrugation on the outside of the liner. To prevent the copper rings shorting out the bottom of each corrugation, and thus reducing the resistance of the liner round its large circumference, and also to prevent any possibility of sparking between conductor and liner, the conductors are first alumina blasted to roughen them and then sprayed with a 5 thou. layer of alumina. This alumina insulation is capable of withstanding the high temperaturesabout 400 C.attained by the liner.

FIG. 2 shows how the two ends of each conductor are joined after the conductor is fitted in a corrugation. The two ends are bent outwards to provide two short overlapping portions clear of the surface of the liner which are brazed together as shown at 5.

-In FIG. 3 the thick-walled torus 2 is made in two halves separated by insulators '30. Mounted within the torus is the corrugated liner 1. The gaseous ring discharge is induced within the liner by means of the two toroidal transformer cores having a primary winding 66 which is connected to a pulse source 68. The axial magnetic field is provided by the windings 6 energized by a D.C. source 69. Although FIG. 3 shows circumferential conductors 4 on the section of liner between lines AA and BB only, in fact each corrugation of the liner contains a conductor, as already described.

'I claim:

1. :In combination with a vessel .for producing a pulsed ring gas discharge, an electrically continuous high resistance liner disposed in the vessel in spaced relation to the Wall thereof and defining the periphery of a toroidal chamber, and means for producing a magnetic field extending axially of the chamber, a series of circumferentially closed conductors disposed in the space between the liner and the vessel wall, and spaced from one another along the axis of the small circumference of the chamber, whereby entry of the axially extending field from said space into the liner is opposed by a magnetic field accompanying currents induced in said conductors.

3 2. The combination according to claim 1 wherein the liner is corrugated and said conductors are disposed in the corrugations.

3. The combination according to claim 2 wherein said conductors are electrically insulated from the liner.

References Cited in the file of this patent UNITED STATES PATENTS FOREIGN PATENTS 1,016,376 Germany Sept. 26, 1957 Spitzer Oct. 27, 1959 10 4 OTHER REFERENCES NYC-7899, The Proposed Model C Stellerator Facility, Aug. 29, 1957, Technical Information Service Exten- 5 sion, Oak Ridge, Tenn., pages 388-392.

Atomic and Nuclear Energy, February 1958, pp. 58, 59.

Nuclear Power, February 1958, pp. 50-52. Controlled Thermonuclear Conference, TID 7558, held at Washington, D.C., February 3-5, 1958. US. atomic Energy Commission Technical Information Service Extension, Oak Ridge, Tenn, pages 222, 223. 

1. IN COMBINATION WITH A VESSEL FOR PRODUCING A PULSED RING GAS DISCHARGE, AN ELECTRICALLY CONTINUOUS HIGH RESISTANCE LINER DISPOSED IN THE VESSEL IN SPACED RELATION TO THE WALL THEREOF AND DEFINING THE PERIPHERY OF A TOROIDAL CHAMBER, AND MEANS FOR PRODUCING A MAGNETIC FIELD EXTENDING AXIALLY OF THE CHAMBER, A SERIES OF CURCUMFERENTIALLY CLOSED CONDUCTORS DISPOSED IN THE SPACE BETWEEN THE LINER AND THE VESSEL WALL, AND SPACED FROM ONE ANOTHER ALONG THE AXIS OF THE SMALL CIRCUMFERENCE OF THE CHAMBER, WHEREBY ENTRY OF THE AXIALLY EXTENDING FIELD FROM SAID SPACE INTO THE LINER IS OPPOSED BY A MAGNETIC FIELD ACCOMPANYING CURRENTS INDUCED IN SAID CONDUCTORS. 